A conventional microbubble-liquid producing apparatus of this type is disclosed in, for instance, Japanese Published Unexamined Application No. 2003-117365(A). The conventional microbubble-liquid producing apparatus comprises an air-liquid mixing pump for aspirating mixture fluid of liquid and air, a resistor for imposing resistance to fluid discharged from the air-liquid mixing pump, and an inverter for controlling the rotation speed of the air-liquid mixing pump, wherein an annular fluid passage having a narrow radial width is formed in a casing of the air-liquid mixing pump and many stirring blades protruding into the fluid passage are formed on the periphery of a bladed wheel.    [Patent Literature 1] Japanese Published Unexamined Application No. 2003-117365However, the aforementioned conventional microbubble-liquid producing apparatus is designed to produce desired air microbubbles at a given time by using the single air-liquid mixing pump. For that purpose, the conventional apparatus has a need to assume its complicated structure comprising the annular fluid passage having the narrow radial width inside the casing and a number of stirring blades protruding into the fluid passage on the periphery of a bladed wheel.
Furthermore, the conventional apparatus requires the inverter for accurately controlling the rotation speed of the air-liquid mixing pump, inevitably to increase its production cost. Besides, in order to perform maintenance and inspection on the air-liquid mixing pump and other components, the complicated and specific structure of the apparatus should be totally known, but at any rate, the maintenance and inspection cannot be performed easily.
The present invention seeks to provide an apparatus for producing microbubble liquid, having a simplified structure to be produced at a moderate price and capable of being maintained and inspected with ease, and further having an advantage of capable of effectively producing microbubble liquid containing fully microscopic air bubbles, and further provide a device for atomizing air bubbles using the aforementioned apparatus.